The One with All the Poker - S1-E18
Continuity mistake: When Chandler and Ross are explaining how Joey cried during their poker game, Joey's coffee mug is blue when he's holding it at the counter, but when Joey walks away from the counter his mug is yellow.
The One with All the Poker - S1-E18
Continuity mistake: After the game at Ross' apartment Chandler takes Phoebe's cursed money, and when Ross wants to settle up with "the big Green poker machine who owes fifteen," Rachel's sitting down at the table in front of Ross, but then it cuts to Rachel who's suddenly standing up near the table. (00:12:30)
The One with All the Poker - S1-E18
Continuity mistake: When the group is sitting around the table in Monica's apartment playing poker, Monica is making something to eat. When she puts it on the table and sits back, we can see a pile of plates on the table on her right side. But in the next shot, the plates are gone. (00:05:35)
The One with All the Poker - S1-E18
Other mistake: During the third game of poker, the bottle of raspberry Snapple on the table has part of its brand name whited out on the label.
Answer: The statements that she's contradicting (that it is common, it happens to every guy, and it's not a big deal), are the things that a woman commonly says to a man who is suffering from erectile difficulty, typically to assuage his bruised ego. However, most men do not believe that these statements are true, as evidenced by Chandler's outburst. He's so caught up in the proof that women are lying about it that he gives himself away.
Rooster of Doom